The present invention relates to devices and methods for delivering, administering or injecting a substance, and to methods of making and using such devices. More particularly, it relates to a device for administering an injectable product, more particularly to an auto-injection device, comprising an insertion mechanism for inserting an injection needle and a delivery mechanism for delivering the injectable product.
Administering devices for automatically administering an injectable product, such as insulin, growth hormones or the like, with one hand are known in many various embodiments. They generally comprise an actuator, e.g., a button, trigger or the like which is pushed, pressed or pulled, an insertion means for inserting an injection needle into a body tissue and a delivery means which delivers the injectable product from a product container of the administering device after the injection needle has been inserted. The insertion and delivery means can be activated by manipulating a trigger, e.g. by hand, such that first an insertion movement of the injection needle and then a delivery movement for delivering the product is performed.
To this end, both the insertion means and the delivery means are provided with a force-generating drive mechanism, e.g., a spiral spring, which is clamped between the insertion and/or delivery means and an abutment, e.g., on or part of the casing of the administering device. The insertion and delivery means can be fixed when the drive mechanisms are tensed, and released or actuated by the trigger. Triggering the insertion and/or delivery means drives them in an insertion direction, i.e., generally along or parallel to the longitudinal axis of the device towards the body tissue.
An exemplary device, an injection pistol, is disclosed in DE 35 27 290 A1. An injection needle is fastened in a casing to a cylinder which can be moved relative to the casing and which can be driven by a spiral spring and moved to a biased position. A piston is arranged within the cylinder and can be moved with respect to the casing, driven by a second spiral spring, and likewise moved to a biased position. The piston and the cylinder interact in such a way that when the injection pistol is triggered, the cylinder is triggered first in order to cause the injection needle to be inserted, and then the piston is triggered in order to cause a product dosage to be delivery into a tissue. The first and second spiral spring are arranged co-axially along the longitudinal axis of the injection pistol. When triggered, the spring driving the cylinder together with the needle is triggered first, and the second spring, acting on the piston, and the piston initially remain at rest with respect to the casing. Once the cylinder has overcome a predetermined distance, the second spring is triggered by the cylinder, such that a delivery is performed. In the injection pistol, both springs are arranged in a fixed position relative to each other and with respect to the casing. Despite a separate drive, on the one hand for the cylinder for inserting and on the other for the piston for delivering, a relative movement takes place during insertion between the cylinder movement for inserting and the piston movement for delivering, such that insertion and delivery cannot be performed completely independently of each other.